Sorry, not sure about "hospital de referencia", but the accurate term in Spanish to talk about sending a patient from a doctor to another (i.e. GP to specialist") is "derivar".
In addition to this, if it is like a guidance for doctors I would use the "usted" treatment

Thank you both very much for your comments (ainaaina, thanks for the 'derivar' tip - I was actually quoting directly from a rather informal Endocrinologist!).
I now understand how a 'hospital de referencia' operates (thanks, pildorilla), but am yet to find the precise English equivalent term. I'll attempt to post the reply after consulting medical contacts in the UK.

A medical contact has come up with this:
"Its called a referral hospital - we don't really have an exact equivalent in UK as all hospitals are referral hospitals we have sort of got rid of the level below which would be something like a district hospital, but the phrase still has meaning to signify a hospital where specialists practise"
Hope it helps any future confusion!

A hospital with multiple specialties is often called a tertiary care center. This term would be recognized by those within the medical profession but would probably not be understood by the general population. This would apply to the US. I am not sure about other English speaking countries. The referring hospital is generally a community hospital.

If you were speaking to the patient I would probably call it a referral hospital, although that isn't a term we commonly use in the US but it should be understood by the patient; however, if you were speaking to a medical professional I would probably call it a tertiary care hospital.